Depth gauge control and lead plug



L. T. STAjRR DEPTH GAUGE CONTROL AND LEAD PLUG Sept. 8, 1936.

2 Sheets-Sheet 1 Filed March 18, 1935 INVENTOR ATTORNEY Patented Sept.8, 1936 UNITED STATES PATENT OFFICE 2,053,448 DEPTH GAUGE CONTROL ANDLEAD PLUG Lewis T. Starr, Dallas, Tex.

Application March 18, 1935, Serial No. 11,663

Claims. (6i. 166-1) This invention relates to the art of cementing wellsand it has particular reference to a depth gauge control and lead plug.

The principal object of the invention is to 5 improve upon conventionalmethods of cementing wells'by providing means for accurately determiningthe depth at which cement is to be pumped and which provisioniseiiective not only in the saving of cement and the time usuallyrequired to complete the job of cementing but is likewise effective ininsuring proper disposition of the cement at the lower end of the wellcasing. For all practical purposes, the cementitious material should beheld under a uniform pressure until it attains a mechanical set. Also,it is required that the mud within the casing be forced out preparatoryto the introduction of the cement and further, it is important that thecement does not rise to any great extent within the well casing and toprevent this, the invention provides means capable of being forced to apredetermined depth within the well casing by fluid under pressure andthis means is instrumental both in preventing the cementitious materialfrom rising in the casing and separating the material from the pressurefluid.

The invention further aims to provide means which may be secured inspaced relation to the bottom of the well casing and at a predetermineddepth therein to function as an operating means I for the depth gaugecontrol,'the latter, as stated,

being the means by which the cement is prevented from rising within thecasing.

With the foregoing objects as paramount, the

invention has particular reference to its salient features ofconstruction and arrangement of parts which will become manifest as thedescription proceeds, taken in connection with the accompanyingdrawings, wherein:--

Figure 1 is a vertical section at the bottom of a well showing the twounits of the invention in position, the depth gauge control being shownunder fluid pressure.

Figure 2 is a detail view of the depth gauge away.

Figure 8 is a perspective view of one of the expansible segments carriedadjacent the upper' Figure 10 is a fragmentary elevation showing one ofthe prongs of the plug in solid and in dotted lines which is theoperative and inoperative positions respectively of the prong.

' Figure 11 is a fragmentary viewv in vertical section of a jointbetween two sections of the casing showing a spider which is used inlieu of the plug shown in Figures 9 and 10.

Figure 12 is a fragmentary view in section of the lower end of a casingwhere a conventional casing guide shoe is used and which elementobviates the necessity for using the lead plug or the spider shown inFigure 11, and

Figure 13 is a modified form of the device shown in Figure 11.5

Continuing with a more detailed description of the drawings, referenceis made primarily to Figures 2 to 8 inclusive. In Figure 2 is shown themounting for the expansible elements, to be described in detail laterand the expansible wings 2. This mounting is shown also in Figure 3 withboth the elements 8 and wings 2 removed and as apparent, the mounting iscomprised of a series of spaced, parallel members 3, the spacing beingbetter shown in Figure 6. Above the spaced members 3 there is a box tand on each of its four sides there is aflixed pairs of members 5, eachpair defining a channel in which the wings 2 are received. Springs 6 aredisposed behind each of the wings in order that they will be normallyurged outward. Each wing is faced with a strap of leather or othersuitable material], the purpose of which will be described presently.

The lower portion of the gauge control is formed into a box likestructure 8 which is hollow to receive a squared expanding element ortrigger 9, shown in detail in Figure 4. A slot H! is provided in the box8 longitudinally thereof and in which slides a dowel pin it secured tothe trigger 9 and which arrangement prevents the trigger 8 from droppingout of the box 8 when the gauge control is suspended in a well. Securedto the bottom of the trigger 9 is a guide formed of light angularmembers it, each of which may be faced with a strip of leather or othermaterial Hi. This guide serves to maintain the control gauge inconcentric relation to the casing as it is forced downwardly therein butit does not interfere with upward passage of cement, the latter beingstopped by the packing washers it, one of which is disposed below theexpanding elements I, another immediately thereabove and still anotherabove the expanding wings 2. Annular recesses I5 are provided toaccommodate these washers.

Referring specifically to the expansible elements I, reference is madeto Figure 8 in which the elements are shown to be segmental so that thegroup will embrace the mounting on all sides. Each element has a tongueI6 receivable in the spaces between the members 3 of the mounting. Whenthe segments I are expanded by the trigger 9, which operation will belater described, there will be a space between each of the segments andto cover which, strips of leather or similar material I! are affixed toone segment whereby the free portion thereof will lie within recesses I8in a companion segment. Thus the spaces are closed against the upwardpassage of cement likely to escape the wiping action of the lowermostpacking washer I4. When the segments I are all assembled in operativerelationship on the mounting, they are embraced by a sleeve I9 ofresilient material such as rubber. It will be understood however thatthe purpose of the sleeve is to retain the segments I in properrelationship on the mounting and to return them to their originalinoperative position after having been expanded.

It is of course apparent that the sleeve has some effect in preventingthe device from floating upwardly and serves to secure the-same inposition in the casing. However, the rubber sleeve may be substituted bya coiled spring or any equivalent means which will retain the segment inplace and return them to their original position. The wings 2 are infact the means by which the device is held against undue upward movementin the casing since the facing I thereon serves to grip the walls of thecasing with suflicient firmness as to resist any back pressure shouldfor any reason the fluid pressure be relieved.

The foregoing substantially describes the depth gauge control and adescription of the construction' and operation of the lead pl will nowbe made.

Reference is made to Figures 9 and 10 in which is shown paired members20, each pair defining a vertical groove or channel 2I in which reposesa prong 22. Normally each of the prongs 22 are disposed in the mannershown in dotted lines in Figure 1 0 and being pivoted at 23 they arecapable of being extended to the dotted position shown in Figure 10 oras shown in Figures 1 and 9. 'A spring 24 serves to extend the prongs 22when the latter are released and in each of the channels 2| there is astop 25 which holds the prongs at right angles to the longitudinal axisof the plug when they are extended.

At either end of the plug there is a packing washer 26 and at its basethere are a series of flexible members 21 which engage the pointed endsof the prongs in the manner shown in Figure 10 to prevent them fromspringing out of the channels or recesses 2| predeterminately.

The pointed ends of each of the prongs are reinforced by metal tips 28and intermediate the ends of the prongs there is provided a protuberance29, preferably of rubber which engages the walls of the casing andserves to guide the same therein.

.In cementing wells in the manner described, it is preferable that thedevices used to control the Cement be constructed of wood or perhapssoft metal in order that there will be no difliculty or -;injury.to thedrill bit when it becomes necessary to proceed with the completion ofthewell subsequent to cementing and since this is true, some parts of thedevices are reinforced with metal when they are constructed of wood.such as the tips of the prongs 22. It will be observed in Figure 4 thatthe upper portion of the trigger 9 is reinforced at 30.

In operation, the lead plug shown in Figures 9 and 10 is first insertedinto the casing and a proper mixture of neat cement is afterwards in-,troduced under pump pressure. Mud is driven out of the casing and passesupwardly outside the walls of the casing as the plug is forced towardthe lower end thereof. This mud sometimes rises which are driven intothe walls of the well by,

pump pressure from the surface. thus held against displacement.

The depth gauge control shown in Figures 1 to 8 inclusive, is thenintroduced into the casing and backed by fluid under pressure such asindicated at 3| in Figure 1.. The depth gauge is thus forced downwardagainst the cement in the casing and the latter is forced upwardlyexteriorly of the casing as shown at 32 in. Figure 1. In thus passingupwardly, the cement urges the mud and water toward the surface and thecement effectively closes any leaks in the casing.

When the depth gauge is forced down to a point where the guide membersI2 engage the lead plug as shown in Figure 1, further pressure upon thedepth gauge will force the mountin downward while the trigger. 9 remainsstationary against the plug. The pointed end of the trigger 3 is thusurged against the curved lower ends of the tongues I6 formed upon theslips I, thereby causing the slips to move outwardly, expanding therubber sleeve I9 against the walls of the casing. As soon asthisactiontakes place, the operator will be immediately apprised due to the factthat there will be a sudden rise on the pressure indicator at thesurface and the fluid The plug is pressure will be maintained at auniform degree for a predetermined period of time to allow the cement toattain a mechanical set after which the pressure is relieved and thedrilling operation may proceed. The elements described remain in thehole and are drilled out as the drilling proceeds.

In some cases, especially deep wells, a casing guide shoe 33 such asshown in Figure 12 is employed and this will obviate the necessity ofusing the lead plug shown in Figures 9 and 10 since the depth is knownand the shoe 33"serves as an actuating means for the depth gaugecontrol, cement being pumped through the opening 34 in the shoe 33 inadvance of the depth gauge.

Some drilling contractors prefer that a column of cement of apredetermined height be left in the casing. In cases of this kind, adevice of the character shown in Figure i1 is employed. This deviceconsists of a spider 35 having set screws 36 in each of its arms whichare interposed between the contiguous ends of two sections of casing,one or more sections from the :bottom of the hole as indicated by thecontractor. The spider does not interfere with the down- 2,068,448wardly against the cement. When the depth gauge reaches the spider 35,the segments are expanded as described in the foregoing and the depthgauge is maintained in a stationary posltion by fluid pressure until thecement attains a mechanical set.

As a modification of Figure 11, the device Shown in Figure 13 isprovided and is comprised of the sleeve 31 of ,wood or other materialhaving three or more leaf springs 38 secured at spaced points to itsperiphery. The upper ends of these springs are bent outwardly as shownand are adapted to lie between the joints of the casing and therebysuspend the sleeve 31 in vthe casing.

Manifestly, the construction shown is capable of considerablemodification and such modification as is considered within the scope andmean ing of the appended claims is also considered within the spirit andintent of the invention.

What is claimed is: 1. In combination with an anchor plug in a wellcementing assembly, a follower plug includ ing a body having a plungeraxially movable therein and radially expansible means actuated by saidplunger to secure said follower plug in a well.

2. In combination with an anchor plug in a a well cementing assembly, afollower plug including a body having a plunger axially movable thereinand radially expansible means actuated by said plunger to secure saidfollower plug in a well, and resilient means surrounding said expansiblemeans for holding the same against displacement.

3. In combination with the lead plug of a well cementing assembly, adepth gauge control plug comprising a group of members disposed radiallyabout a common axis, a plunger movable through said axis to radiallyexpand said members upon engagement with said lead plug and packingmeans carried by said control plug.

4. In combination with the lead plug of a well cementing assembly, abody having an axially movable plunger, a plurality of members groupedradially about the longitudinal axis of said body and capable of outwardmovement upon upward thrust of said plunger when the latter impingessaid lead plug, expansible means for limiting the movement of saidmembers, packing means-carried by said body and means to limit the axialmovement of said plunger.

5. In combination with the lead plug in a well cementing assembly, adepth gauge control plug comprising a body, the upper section of whichis surrounded by a plurality of radially expansible segments, resilientmeans surrounding said segments to limit the degree of radialdisplacement of said segments, an axially movable plunger, a guidetherefor in the lower section of said body, said plunger having means toengage and expand said segments upon engagement thereof with said leadplug in a well.

LEWIS T. STARR.

